Ground penetrating radar systems have been used for some time to image objects buried beneath the ground. As with all radar systems high frequency, or short pulse width radars are very good at providing detailed resolution of objects being imaged. However conductive attenuation and dissipative losses due to soil conditions and moisture increase dramatically with frequency, limiting the ability of to penetrate deeply into the soil.
Lower frequency radar systems, or those with wide pulse widths are able to penetrate much more deeply into the ground as they are much less affected by the dissipative characteristics of the soil and sand. Lower frequency radar yield less resolution than high frequency radar, thereby limiting its ability to define images objects. Generally, however, objects of interest at greater depths are larger or multiple limiting the need for high resolution.
As a result of these characteristics, ground based radar systems are chosen based on the types of imaging required. High frequency radar systems are chosen to provide great detail of shallow objects. An application of a high frequency radar system in a military context would be to locate land mines or improvised explosive devices which are buried only a few inches from the surface. Low frequency radar systems are chosen to find deeper objects such as bunkers, weapons caches and other larger objects buried at greater depths, but which are also larger object that do not require the resolution of the high frequency radar systems.
There are times, however when it is desirable to image both shallow objects at high resolution and deep objects. Current systems require the use of two separate radar systems and all their associated antennas and electronics. It would be advantageous in these instances to have a single ground penetrating radar system that is capable of generating a variety of pulse widths including both low frequency, wide pulses and high frequency, short pulses to enable both deep and shallow operation on demand, as well as potentially an intermediate frequency that provides greater resolution than the low frequency pulses at depths greater then the high frequency pulses.